Aluminum (A1) accumulation by bone can cause vitamin D-refractory osteomalacia, characterized by bone pain, proximal muscle weakness and marked disability, in adults with end-stage renal disease (ESRD), who are otherwise well managed by dialysis. Outbreaks of this syndrome due to high A1 levels in dialysate can be prevented by water purification. However, both "dialysis encephalopathy" and aluminum related osteomalacia have been described prior to the initiation of dialysis, both in infants and adults with advanced chronic renal failure. Moreover, large doses of A1-containing phosphate binders are ingested by patients with ESRD to control hyperphosphatemia and secondary hyperparathyroidism. A strong relationship between the plasma A1 levels and the oral A1 intake from phosphate binders was found in children undergoing CAPD. The incidence of this disorder is uncertain; but it may be 20=25% of dialysis patients, or even higher, with longer duration of dialysis. The clinical features and prevalence of Al-related bone disease in pediatric patients with renal failure are unknown. The aims and objectives of this clinical study are: 1) to identify both the clinical characteristics and the prevalence of A1-related bone disease in a large population of dialyzed children by bone biopsies. The value of non-invasive tests, such as plasma A1, desferrioxamine (DFO) and serum parathyroid hormone (PTH) will be evaluated; 2) Patients with Al-related bone disease will be randomly assigned to a double blind long-term treatment with DFO or placebo. This will include serial measurement of A1, calcium, PTH, growth rate and bone biopsies before and one year after treatment with DFO or placebo. The effect of DFO on A1 removal during CAPD, CCPD and hemodialysis will be evaluated; 3) The long-term effect of a non-aluminum containing phosphate binder, calcium carbonate, on serum phosphorus and plasma aluminum will be evaluated. The present study is intended to provide data on the diagnosis, treatment and prevention of this important syndrome in a large population of children on dialysis.